1. Field of the Invention
The present invention relates in general to a guidance control for an agricultural implement pulled by a tractor and more specifically relates to a guidance control that operates in association with the three point hitch of the tractor to provide a positive control for horizontal movement of the hitch.
2. Description of the Prior Art
The present invention is adapted to be utilized with the three point hitch of a tractor to control the travel of an agricultural implement pulled by the tractor through a field of row crops. Under such circumstances, it is highly important that the implement be positioned relative to the rows so that destruction of the crop does not result.
Until recently, guidance of such implements was controlled solely by the operator of the tractor guiding the tractor wheels with respect to the crop rows in front of him and relying upon the fact that normally the implement will be following the tractor in a proper position with respect to the crop rows. This means that the tractor operator must be conscious at all times of the relationship of the tractor to the crop rows and skillful and conscientious driving is required to maintain proper steering of the tractor.
In recent years, guidance systems have been developed to properly position an implement with respect to the crop rows even though the tractor which it follows may be improperly positioned thereto. Fleischer et al. U.S. Pat. No. 4,930,581 is an example of one such guidance system. The Fleischer et al. patent discloses the use of a control hitch mounted to a conventional three point tractor hitch and positioned between the hitch and the tool bar of an implement which is rotatably mounted to the control hitch. Sensing devices are associated with the implement for activating hydraulic circuitry that causes rotation of the implement with respect to the control hitch to properly position the implement relative to rows of crops. Another type of guidance system that is known in the art is manufactured and sold by Orthman Manufacturing, Inc. and involves a somewhat rectangularly shaped frame type structure, the movement of which is controlled by a programmable microprocessor based controller to move the pull links of a three point hitch from side to side.
Although the above systems appear to provide improved performance for guidance of an implement following a tractor, such systems are unnecessarily complicated and relatively expensive to manufacture. Furthermore, they cannot be manually activated to control horizontal movement of a three point hitch. In contrast to the prior art devices, the present invention provides a relatively simplistic means for manually or automatically efficiently and conveniently controlling the horizontal movement of a three point hitch.